Peculiar ZnO nanopushpins and nanotubes synthesized via simple thermal evaporation

ZnO nanostructures with peculiar morphology were synthesized in large quantities via catalyst-free thermal evaporation. Both ZnO nanopushpins with very thin and flat cap on top of the nanorods, and regular hexagonal nanotubes, can be obtained in the same run of growth in different regions. The ZnO nanopushpins and nanotubes were characterized by using scanning electron microscopy and transmission electron microscopy. Cathodoluminescence measurements revealed that the emission from oxygen vacancy overwhelmed that of the near band gap in the as-grown ZnO nanotube arrays.